When it comes to sail trimming, regardless of the hull shape, all type of sailboats works more or less on the same principles. In this post, we will talk about small differences when it comes to sail trimming on a Nautitech Catamaran.
Before starting, we should mention this; all sailing basics are still applicable on catamarans. In the end, a sailing vessel is a sailing vessel.
When we say sail trimming for catamarans, we basically talk about the giant mainsail of the catamarans where there is a slight difference with the monohulls.
No Boom Vang, just main sheet
The biggest difference is in monohulls, fine-tuning of the mainsail boom vang and the tension of the backstay play a highly important role while for catamarans we take care of everything with the traveler and the main sheet. With the boom vang, you can change the boom movement horizontally to control the curve at your mainsail. In Catamarans, we do everything with the mainsheet and the traveler. Most of the catamarans have nicely arranged lines and winches to do the whole operation easily. This perhaps leaves less room for fine-tuning the mainsail however definitely easier operation.
Sailing Upwind in light wind
For the main sail;
Keep tell-tales flying ( top to Bottom), not dancing
Keep their mainsail not too high
Boom up in the center line of the boat using the traveler
Once your traveler is set, you will be able to set your main sail curvature by adjusting the main sheet.
Upwind in heavier wind Sail Trimming
If the wind picks up when sailing upwind
The first thing would be to ease the traveler down. Once the wind starts to get about 10 to15 kts, the traveler should be eased almost down to leeward. Remember on Catamarans, they don’t have the boom vang so what is controlling the boom height and the leech tension in the main is the main sheet itself. Quite often the main sheet needs to be used to get that setting right and then play the traveler up and down. Remember: the main sheet controls the leach of the mainsail.
Tip: You can check the indication of too much main sheet on that is called “not enough twist” in the top of the mainsail causing the mainsail to stop. You should have a look up, you will see top couple of leech tell-tales right at the back of the sail starting to dance around instead of stable.
Catamarans don’t heal as much as the monohulls. Catamaran experience will definitely change the way you trim your sails comparing to monohulls. This requires practice and getting to know your boat of course. The more you point, you will see the limits of your catamaran and the best working curve of your mainsail. Here every skipper should play with the main sheet to feel the best curve and the performance.
The headsail is not different than any mono hull sailing boat.
There are also tell-tails in the headsail. It is a good indication of how your headsail is set. Telltales should be horizontally parallel to each other. If the headsail is too tight outside tales will start to dance. If it is too loose then the inside tails will start to move.
Leeward not horizontal = Over trim
Windward not horizontal = Under trim
As a sailing basic, by moving genoa/jib car, the sheeting angle of the genoa is altered changing the tension in the leach and foot and altering the shape of the sail. The car should be adjusted in a way that when your genoa sheet continues, it should divide the sail equally in two.
Transition from upwind to downwind on catamarans
When you steer down from 40 to 90 degrees off the wind, simply ease the mainsheet, headsail sheet and drop the traveler down the track.
Try to avoid the bubble at the front of the sail. If you have got the front of the sail sort of back winding into you or a bit of a bubble there, that is a good indicator that you probably used a little bit too much.
Tip: Especially when you are going to 90 degrees or more off the wind, make sure that your mainsail is not hitting hard against the shrouds for long passages and long periods of time. This will damage your mainsail eventually.
As summary, sailing basics and handling the sails are based on the same principles for hundreds of years. When you are sailing with a catamaran, you will see the importance of the mighty mainsail and how to control it by practicing.
Fair winds and following seas!